My house has central airconditioning. Being a cheapskate though, I prefer not to run it. My house has a finished basement and a sump pump. I run a dehumidifier there. The house is in northern Ohio, where it is currently very hot and very humid.
It is hot enough to overcome my cheapness and run the AC, so I’m doing that. My question is, should I also be running the dehumidifer, or it that all just wasted on the AC?
Not an expert here, but running both would probably be redundant. A/C does a pretty good job of dehumidification.
I have a finished basement and run a dehumidifier there in the summer months, even if the A/C is running. Due to below-grade location it is more humid than the upper floors of the house and tends to be cool and damp, and get mildew. So if your situation is similar I would not say the dehumidifier is redundant.
the AC dehumidifies the air. a dehumidifier in the basement dehumidifies the air in the basement.
the dehumidifier has a humidistat which should be set at a level that keeps dampness out of the basement so it doesn’t have a musty smell (or whatever level you want) to keep it locked on (humidistat set to never turn off) full time would likely be a waste.
if the AC is ducted to the basement then it would run to dehumidify the air in that zone. if the dehumidifier ran in the basement as well then it might not run the AC on behalf of the basement as much. it depends on how many AC zones you have.
a dehumidifier alone in a basement can make it very comfortable.
I would say no as long as the A/C is getting the job done as far as cooling and keeping the basement from getting too humid. If the A/C isn’t cooling well enough for your tastes, by all means run the dehumidifier. An A/C unit will dehumidify the air passing though it as well as cooling it, but the less work done to remove moisture the more work can be done to cool the air.
If the AC unit is a whole house central system and can get the job done you’re better off having just the AC unit on.
The dehumidifier is basically a small AC unit that takes in air, passes it over the cooling coils (to get the water to condense on the coils just like a cold drink gets sweat on it). The water drips off the coils and is collected in a bucket or led by a hose to a drain.
After the air passes through the cooling coils and loses its water it then passes through the heating coils and picks up heat. Though dryer now, it exits the humidifier at a temperature warmer than it entered.
So while the dehumidifier will help dry out the air it also adds some waste heat to the air in the basement. Being a smaller unit than a typical central AC it is probably not as efficient as your central AC.
So, as long as you still reach a decent comfort level, its better (cheaper) to let your AC unit dehumidify the basement instead of running both.
Also, if your sump isn’t covered buy a cover for it. Most big box hardware stores have cheap plastic covers for the sump hole. It will slow down sump evaporation and help keep the basement dry.